Adolescents and young adults who use drugs are at high risk for infection with HIV, STDs and other diseases with similar transmission dynamics. Although several age-appropriate and effective HIV, STD and disease prevention efforts have been identified for young substance abusers, most interventions have been narrow in focus and are generally not structured to readily address changing patterns of drug use among adolescents that place them at risk for infection with these diseases. In this application, we propose to develop and evaluate an interactive, computer-assisted HIV, STD and disease prevention program for young substance abusers that incorporates effective components of both prevention science and educational technologies. We plan to develop this program with the input from the target population of adolescents and young adults. We also plan to conduct two randomized, controlled trials to evaluate the benefit of including this program in HIV and disease prevention efforts with youth in substance abuse treatment. The first study will be an efficacy study conducted in a research clinic setting with adolescents, and the second study will be an effectiveness study conducted in a community-based substance abuse treatment clinic setting with young adults. In so doing, we will evaluate the ability of the program to promote accurate knowledge about HIV and other diseases, promote self-efficacy to reduce risk behavior and change actual rates of risk behavior among young substance abusers in both of these settings. This computer-based program will be designed to promote the increased adoption of effective HIV and disease prevention science for this population. New information about changing patterns of drug use and HIV risk behaviors can be readily incorporated into the program as it becomes available. The program can be easily exported and able to be applied with fidelity. Importantly, the program will be structured such that a therapist or educator may customize the program content for use by various sub-populations of substance-abusing adolescents and young adults. Thus, the program will be able to address risk factors specific to each young drug user. This program may address many of the challenges associated with the current delivery of evidence-based HIV prevention programs to this population.